1. Field of the Invention
The present invention relates to lightning arrester devices for the protection of electric lines, and especially medium-high voltage overhead lines wherein a visual indication is given of a short-circuit condition in the arrester.
2. History of the Related Art
Lightning arrester devices for the protection of medium high-voltage overhead lines are known generally to comprise an insulating body provided with two connection capsules or electrodes respectively connected to the electric line to be protected and to earth or ground. This body contains an element which, in normal operation, ensures mutual insulation of said two capsules electrodes, while being capable of becoming momentarily current-bearing under the effect of a sudden rise in voltage due to lightning striking the line. Once the high-voltage shock wave has been dissipated, the element must become perfectly insulating again.
However, this return to insulating state sometimes takes place under poor conditions, due in particular to damage of the insulation element, in which case a so-called "continuation" current appears which in fact constitutes a short-circuit on the electric line. As an electric line most often coprises a large number of lightning arresters, it is difficult in practice to determine which is the device producing the "continuation" current and the short circuit.